Hello,

Am 15.07.2020 um 06:32 Strahil Nikolov wrote:
How  did you configure the network on your ubuntu 20.04 Hosts ? I tried  to 
setup bridged connection for the test setup , but obviously I'm missing 
something.

Best Regards,
Strahil Nikolov


on the hosts (CentOS) the bridge config looks like that.The bridging and configuration is handled by the virtualization software:

# cat ifcfg-br0
DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.1.21
NETMASK=255.255.0.0
GATEWAY=192.168.1.1
NM_CONTROLLED=no
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no



Am 15.07.2020 um 09:50 Klaus Wenninger wrote:
> Guess it is not easy to have your servers connected physically for a try.
> But maybe you can at least try on one host to have virt_fenced & VM
> on the same bridge - just to see if that basic pattern is working.

I am not sure if I understand you correctly. What do you by having them on the same bridge? The bridge device is configured on the host by the virtualization software.


>Well maybe still sbdy in the middle playing IGMPv3 or the request for
>a certain source is needed to shoot open some firewall or switch-tables.

I am still waiting for the final report from our Data Center techs. I hope that will clear up somethings.


Additionally I have just noticed that apparently since switching from IGMPv3 to IGMPv2 and back the command "fence_xvm -a 225.0.0.12 -o list" is no completely broken. Before that switch this command at least returned the local VM. Now it returns:
Timed out waiting for response
Operation failed

I am a bit confused by that, because all we did was running commands like "sysctl -w net.ipv4.conf.all.force_igmp_version =" with the different Version umbers and #cat /proc/net/igmp shows that V3 is used again on every device just like before...?!

kind regards
Stefan Schmitz


На 14 юли 2020 г. 11:06:42 GMT+03:00, "stefan.schm...@farmpartner-tec.com" 
<stefan.schm...@farmpartner-tec.com> написа:
Hello,


Am 09.07.2020 um 19:10 Strahil Nikolov wrote:
Have  you  run 'fence_virtd  -c' ?
Yes I had run that on both Hosts. The current config looks like that
and
is identical on both.

cat fence_virt.conf
fence_virtd {
         listener = "multicast";
         backend = "libvirt";
         module_path = "/usr/lib64/fence-virt";
}

listeners {
         multicast {
                 key_file = "/etc/cluster/fence_xvm.key";
                 address = "225.0.0.12";
                 interface = "bond0";
                 family = "ipv4";
                 port = "1229";
         }

}

backends {
         libvirt {
                 uri = "qemu:///system";
         }

}


The situation is still that no matter on what host I issue the
"fence_xvm -a 225.0.0.12 -o list" command, both guest systems receive
the traffic. The local guest, but also the guest on the other host. I
reckon that means the traffic is not filtered by any network device,
like switches or firewalls. Since the guest on the other host receives
the packages, the traffic must reach te physical server and
networkdevice and is then routed to the VM on that host.
But still, the traffic is not shown on the host itself.

Further the local firewalls on both hosts are set to let each and every

traffic pass. Accept to any and everything. Well at least as far as I
can see.


Am 09.07.2020 um 22:34 Klaus Wenninger wrote:
makes me believe that
the whole setup doesn't lookas I would have
expected (bridges on each host where theguest
has a connection to and where ethernet interfaces
that connect the 2 hosts are part of as well

On each physical server the networkcards are bonded to achieve failure
safety (bond0). The guest are connected over a bridge(br0) but
apparently our virtualization softrware creates an own device named
after the guest (kvm101.0).
There is no direct connection between the servers, but as I said
earlier, the multicast traffic does reach the VMs so I assume there is
no problem with that.


Am 09.07.2020 um 20:18 Vladislav Bogdanov wrote:
First, you need to ensure that your switch (or all switches in the
path) have igmp snooping enabled on host ports (and probably
interconnects along the path between your hosts).

Second, you need an igmp querier to be enabled somewhere near (better
to have it enabled on a switch itself). Please verify that you see
its
queries on hosts.

Next, you probably need to make your hosts to use IGMPv2 (not 3) as
many switches still can not understand v3. This is doable by sysctl,
find on internet, there are many articles.


I have send an query to our Data center Techs who are analyzing this
and
were already on it analyzing if multicast Traffic is somewhere blocked
or hindered. So far the answer is, "multicast ist explictly allowed in
the local network and no packets are filtered or dropped". I am still
waiting for a final report though.

In the meantime I have switched IGMPv3 to IGMPv2 on every involved
server, hosts and guests via the mentioned sysctl. The switching itself

was successful, according to "cat /proc/net/igmp" but sadly did not
better the behavior. It actually led to that no VM received the
multicast traffic anymore too.

kind regards
Stefan Schmitz


Am 09.07.2020 um 22:34 schrieb Klaus Wenninger:
On 7/9/20 5:17 PM, stefan.schm...@farmpartner-tec.com wrote:
Hello,

Well, theory still holds I would say.

I guess that the multicast-traffic from the other host
or the guestsdoesn't get to the daemon on the host.
Can't you just simply check if there are any firewall
rules configuredon the host kernel?

I hope I did understand you corretcly and you are referring to
iptables?
I didn't say iptables because it might have been
nftables - but yesthat is what I was referring to.
Guess to understand the config the output is
lacking verbositybut it makes me believe that
the whole setup doesn't lookas I would have
expected (bridges on each host where theguest
has a connection to and where ethernet interfaces
that connect the 2 hosts are part of as well -
everythingconnected via layer 2 basically).
Here is the output of the current rules. Besides the IP of the guest
the output is identical on both hosts:

# iptables -S
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT

# iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
SOLUSVM_TRAFFIC_IN  all  --  anywhere             anywhere
SOLUSVM_TRAFFIC_OUT  all  --  anywhere             anywhere

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Chain SOLUSVM_TRAFFIC_IN (1 references)
target     prot opt source               destination
             all  --  anywhere             192.168.1.14

Chain SOLUSVM_TRAFFIC_OUT (1 references)
target     prot opt source               destination
             all  --  192.168.1.14         anywhere

kind regards
Stefan Schmitz



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